Branching morphogenesis is a complex process that occurs during the development of the salivary gland, lung, kidney, prostate, and mammary gland. Using the salivary gland organ culture system, some molecules required for branching have been identified, including integrins, the extracellular matrix (ECM), and the actin cytoskeleton, but mechanisms remain unclear. The first step in branching is formation of clefts in the epithelial surface. Collagen III has been localized to clefts, indicating it may play a role in cleft formation. Integrins are heterodimeric molecules, which span the plasma membrane and mediate interaction of the ECM with the actin cytoskeleton and are, therefore, likely involved in coordinating cell movements and/or shape changes involved in branching morphogenesis. This proposal will address the role of integrins and actin cytoskeleton in submandibular gland development with three specific aims: 1) identify the role of collagen III in cleft formation, 2) define the actin rearrangements and regulators required for cleft formation, and 3) determine if there is an adhesion complex assembled at the sites of cleft formation. Understanding the composition and function of cell-matrix contacts in salivary branching morphogenesis will lead to further understanding of complex developmental processes and provide insights that may facilitate development of rational approaches for salivary gland regeneration in cancer and Sjogren?s syndrome patients.